The present invention relates to an image output device for print-outputting (printing) or transmitting image information read from a document and image data received from an external device, which is applicable to a printer-copier, a printer with an image reader connected thereto or integrated therewith, a facsimile, and the like.
In recent years, printer-copiers (including a combination model also functioning as a facsimile) have been used in an office area (xe2x80x9cOAxe2x80x9d) network. On the other hand, a print system composed of a printer with an image reader connected thereto has also been used in practice because of its usability as a copier in which an image read from an original (document) is transferred directly to the printer and printed without the intervention of a computer. If an automatic document feeder (ADF) is used in such an image output device which selectively outputs the image read from the document or received from an external device (for printing or facsimile transmission), the operation of copying or transmitting a large number of documents can be performed with improved efficiency as in a commonly used copier.
In a conventional image output device, once a copy job operation is initiated in which an image is read from a placed document and outputted (for printing or transmission), the output of image data received from an external device is disabled till the completion of the copy job operation. Even during the execution of the copy job operation, however, the receipt of a print job in which an image is outputted from the external device, i.e., the process of receiving and temporarily storing data is performed.
If some trouble occurs during the reading of a document and disables the read operation, the conventional image output device is brought into a substantially non-operating state (system down), when viewed from the external device, and remains therein till the trouble is removed and the read operation is enabled. Unless the user promptly takes the proper measures, not only the copy job but also the print job stagnates. One type of potential trouble is the hang-up of a processor for controlling the image reader. In case of hang-up, the user is required to press a reset switch provided in the image reader. Although the reset operation is supposed to immediately cancel the hang-up of the processor and enable the read operation, the operation of resetting printer hardware or an instruction to reset printer software from the external device to the printer occasionally causes switching to an operational mode in which the print job is executed, so that the reading function is not used afterwards. Even when the processor is hung up, during a period which the read operation is not performed, an instruction to execute the copy job is not received after the hang-up of the processor so that the reading function remains unusable unless the reset operation is performed.
It is therefore an object of the present invention to minimize the duration of a period during which the read operation is disabled by promptly canceling the hang-up of the processor for controlling the reading of the document.